1. Field of the Invention
The present invention relates to a microprogram control store element (CSE) in a data processing system, and more particularly to a CSE comprised of a read-only store (ROS) and a writeable control store (WCS), dynamically changed during data processing by transfer of microcode from main storage to the WCS, and wherein the WCS is utilized to provide a substitute microinstruction for a known erroneous microinstruction accessed from the ROS.
2. Related Patent Applications
The following applications, including this application assigned to the assignee of this application, have been filed on even date herewith:
1. Ser. No. 269,246 entitled "A Binary Number Substitution Mechanism In Microinstruction Addressing Apparatus" invented by R. J. Pedersen.
2. Ser. No. 269,147 entitled "An Improved Binary Number Substitution Mechanism" invented by F. T. Blount; and
3. Ser. No. 269,148 entitled "Microcode Control of Microinstruction Substitution In A Control Store Mechanism" invented by E. A. Nadarzynski et al.